NYSE: X supplies JBII with feedstock and buys fuel from JBII. They have an ongoing relationship, likely an off-take agreement. Anybody can fill up at your local Exxon station but not anybody can show up to NYSE: X with tanks of fuel and except them to buy them, especially since each tanker must be tested upon receipt.
It's a bit more complex the relationship JBII has with NYSE: X than filling up your car and grabbing a twinkie inside while it's filling.
I'm thinking the NYSDEC mentioning US Steel in JBII's permit is a pretty big hint. Most huge companies won't allow their names to be used in marketing print aka PRs.
Just because something hasn't been released doesn't mean there isn't a partnership. I remember asking IR about Crayola a few months before we finally got the announcement. The answer I received was that something could be announced when both parties were ready. Sure enough it was. Expect the same with US Steel.